Smoke generator



Nov. 5, 1963 D. H. YORK ETAL SMOKE GENERATOR 2 Sheets-Sheet 1 H m Hm mm W8. 3 m om. 8 er 5 @E INVENTORS DOUGLAS H. YORK LEONARD GREINER ATTORNEY Nov. 5, 1963 D. H. YORK ETAL SMOKE GENERATOR mm mm 2 Sheets-Sheet 2 Filed Jan. 12, 1961 5 m w mKR m mm 0 M H w a 5 mm L N m mm W United States Patent 3,109,821 SMOKE GENERATOR Douglas H. York and Leonard Greiner, Chesterfield County, Va., assignors to Texaco Experiment Incorporated, Richmond, Va., a corporation of Virginia Filed Jan. 12, 1961, Ser. No. 82,351 4 Claims. (Cl. 252-359) This invention relates to smoke generating devices. More particularly, it relates to an improved two-compartment smoke generator capable of producing smoke dispersions for purposes of cloud seeding, signalling, insecticide dispersing, etc.

The use of two-compartment devices for smoke generation is known; however, the development of such devices was necessitated by the need for producing voluminous clouds of smoke not possible with conventional smoke candle-s. Although the references to these devices purported improvement in smoke output, they failed to make mention of efficiencies based on thermodynamic calculations.

The present invention is concerned with improvement in the efficiency of smoke generating devices and unlike previous designs, the devices of this invention operate in a near steady-state condition wherein the dispersant is heated only to melting through the controlled transfer of heat to the chamber containing the dispersant. In this way, the dispersant is not decomposed by superheating, nor is there heat lost by way of the molten dispersant. Heat is therefore absorbed by the dispersant at a rate proportional to the dispersant vaporization rate.

The controlled utilization of heat manifests further advantages over conventional two-compartment designs. Previously, satisfactory operation was usually only possible when some additive was added to the dispersant which lowered the melting point thereof. In some cases such as in signalling as much as 50 weight percent of a colorless additive was necessary to be added to a dye dispersant to provide a good colored smoke. Obviously, since the additive added was colorless, it contributed nothing to the actual smoke cloud. Since it requires approximately half of the available heat to melt and vaporize the additive, such heat from a thermodynamic evaluation must be considered wasted.

The present invention comprises an improved two-compartment smoke generator which does not require the addition of additives, and is an improvement in the efficient use of fuel over prior devices.

In addition, one embodiment of the smoke generator of this invention is floatable in water, in the event it is desired to use the device in marine type operations.

An object of this invention therefore is to provide an improved two-compartment smoke generator having simplified construction and having a high efficiency in fuel consumption.

Another object of this invention is to provide an improved two-compartment smoke generator capable of producing dense smoke clouds from a dispersant material.

A further object of this invention is to provide an improved smoke generator which operates in a near steadystate condition wherein the dispersant material is heated only to melting temperatures.

Another object of this invention is to provide a floatable smoke generator capable of producing dense signal clouds of smoke.

Further objects of the invention will be apparent from a consideration of the following description.

Briefly, the smoke generator of this invention comprises a container provided with an open end, a fuel reservoir which contains a suitable fuel, a dispersant reser- 3,109,821 Patented Nov. 5, 1963 voir adjacent to said fuel reservoir and adapted to contain a dispersant, eg a dye, concentric inner and outer fines disposed through said dispersant reservoir, nozzle means disposed between said fuel and dispersant reservoirs, said inner flue providing communication between said nozzle and the open end of said container, said outer flue providing communication between said nozzle and said dispersant reservoir, orifice means providing a passageway between said dispersant reservoir and said nozzle, and ignition means.

The following is a description of specific embodiments of the invention which are illustrated in the accompanying drawings, wherein:

FIGURE 1 is a side view of a smoke generator device embodying the invention with essential components thereof in phantom;

FIGURES 2n and 2b are longitudinal sections of the device shown in FIGURE 1 taken along line 22;

FIGURE 3 is another embodiment of the smoke genera-tor device of the invention showing a longitudinal section thereof.

Referring particularly to FIGURES 1, 2a, and 2b, the smoke generator shown comprises a cylindrical outer shell 10. A closure plug 14 is attached to the rear end of the outer shell by means of a series of machine screws such as at 16 and 18. A conventional O-ring 20 is disposed Within annular space 22 of the plug to seal the plug within the outer shell.

The forward end 12 of the outer shell 10 remains open and a cylindrical fuel reservoir unit 24 and a cylindrical dispersant reservoir unit 26 are inserted therethrough to be positioned concentrically within the outer shell.

The fuel unit 24 comprises a cylindrical shell 25 suitably attached to a circular end plate 32 which defines a cup-shaped fuel reservoir chamber containing therein packing insulation 39 and a solid fuel block 40. Attached to the end plate 32 by suitable means such as machine screws 33, are chamber rings 28 and 29* and shell gasket 31. A suitable igniter train is provided to ignite the forward end of the fuel block 40. The illustrated igniter train comprises an electrical connector 42, lead wires 43, and electrical igniter '44. The open forward end of the fuel unit 24 is fitted into the reservoir base member 48 of the dispersant reservoir unit 26.

The unit 26 of the illustration comprises a cylindrical shell 27, annular base 48, forward end member 34 and dye block 52. A filter screen 46 is suitably attached to base 48. The base 48 contains an annular chamber 58. A nozzle indicated generally at 50 is suitably afiixed within a central opening of base 48. The nozzle 50 is preferably a right angle aspirator-atomizer type of assembly and comprises a gas orifice 60, a right angle aspirator 64, and a third orifice 62 leading into an outer chimney duct 66.

Suitably attached to the forward end of shell 27 is an annular end plate 34. Attached to the plate 34 by suitable means such as machine screws 37 are chamber rings 35 and 36 and shell gasket 38. End plate 34 is provided with a central opening through which a threaded fitting 51 is inserted and a spacer nut member 53 is threadable thereon. Concentric with shell 27 are two cylindrical flue members 54 and 56 which define a double-walled chimney duct 66. The flue members 54 and 56 are suitably secured to nozzle 50' and spacer nut member 53.

Flue member 54 contains passageways such as 72 and 73 for communication between duct 66 and dye reservoir 70. Reservoir 70 is defined by shell 27, end plate 34, and outer flue member 54. Inner flue member 56 defines the inner chimney 68.

A chimney extension 78 is suitably engaged to a nut member 74 containing gasket 76. Nut member 74 is threadably attached to fitting 51 to provide a continuation of chimney 68 into the extension.

The operation of the smoke generator illustrated in FIGURES 1, 2a, and 2b is as follows. Upon ignition through the igniter train, the forward end of the fuel block burns liberating hot combustion gases which flow through screen 46, into the chamber 58 of reservoir base 48, and through the orifices 160 and 62. The gases passing through orifice 62 flow through the double walled chimney duct 66, through passageways 72 and 73 and into the reservoir 70 thereby building up pressure on dye block 52. The hot gases flowing through orifice at high velocity create a low pressure region at the orifice 64. The hot gases in chamber 58 and in chimney duct 66 transfer heat to the surfaces and cause the dye to melt. As a result, a slight pressure build-up is created causing melted dye to pass into orifice 64. The resulting pressure differential in the reservoir and the region of the orifice 64 causes molten dye to be aspirated into the gas stream flowing through orifice 60. Subsequently, the dye is atomized and vaporized or sublimed by the high velocity gas stream as it flows through chimney 68, extension 78 and into the cool atmosphere, where it condenses as minute particles to yield dense signal clouds of smoke.

The composition of the dispersant (smoke agent) is preferably one having low melting and high decomposition temperatures. -A particularly suitable dye is commerical dimethylaminoazobenzene, Color Index 19, which is a yellow dye. It melts at about 120 C., decomposes at about 250 C. and has a sublimation temperature below 120 C. The reservoir may be filled by melting and pouning the dye therein, which on cooling forms a hard block. Alternatively, the dye block may be preformed by consolidating the powdered dye under pressure to form the desired block which is then placed in the dye reservoir.

Any suitable intimately mixed fuel mixture may be used for the fuel block. The desirable characteristics of the fuel mixture are that it have a low linear burning rate, a large volume of gaseous combustion products, a large amount of heat liberated, and a moderate reaction temperature. A particularly suitable fuel useful in this invention is a pressed block of intimately mixed ingredient-s as follows:

The ignition of the smoke generator can be achieved by any conventional igniter means depending upon the use of the smoke generator. The igniter means shown in FIGURE 20 has been found particularly suitable. The lead wires 43 are preferably of very fine insulated armature wire of small diameter whereby the flow of hot gases is not restricted. The igniter mixture used may be any of the conventional types. Particularly suitable is a composition consisting of a slurry of nitrocellulose in ethyl acetate and 1 part PbO 1 part Cu O, 1 part silicon powder which are well mixed.

In the operation of the smoke generator using the dye mentioned above, it was determined that the relative proportion of dye vaporized to fuel consumed was about 1 to 1. This ratio was based upon the complete vaporization (without decomposition) of commercial dimethyl- 'amino-azo-benzene without addition of melting point depressants such as those normally used.

Referring now to FIGURE 3, there is shown another embodiment of the smoke generator of this invention. The modification comprises a fuel reservoir unit 80 and a dye reservoir unit 82. The fuel unit comprises a cylindrical cup-shaped container having side wall 84, base 88, flange member 86, electrical connector 90, lead wires 92,

and electrical igniter 94. A fuel block 96 is contained within the fuel unit.

The dispersant unit 82 comprises a cylindrical cupshaped container having side wall 100, an annular dishshaped base 102, and flange members 106 and 108. Chimney unit 1-12 contains outer flue 116 which has a flared internally threaded portion 104. The flanged portion of flue 116 is suitably attached to a central opening in base 102. Fine 114 forms an outer annular chimney duct 140 with flue 116. Flue 114 forms an inner cylindrical chimney duct 134-.

An externally threaded hollow nozzle assembly is threaded into the threaded flanged portion 104 of flue 116, and flue '114 fits snugly around a protrusion 132 of the nozzle. An externally threaded member 142 containing an orifice tube 136 is threaded into the hollow nozzle 110. Aspirating orifice 138 communicates with orifice tube 136 and annular chamber 144 formed in the hollow of the nozzle by orifice tube 136 and member 142. A passageway 146 in nozzle 110, an annular chamber 147, and a series of openings such as 148 in flared portion 104 permit the dispersant material .150 in reservoir 152 to pass into chamber 144. Orifice passes through nozzle 110 and communicates with duct 140.

Outer fiue 116 contains a series of holes 154 which permit communication of duct with reservoir 152.

The flues 1.14 and 116 are suitably attached to an externallly threaded member 118. An annular closure plate 124 is secured to flange member 106 by suitable means such as nut 128, cap screw 126 and sealing gasket 130. The flues and member 118 pass through a central opening of the closure plate 124 and are secured thereto by means of nut 120 threaded onto member 118 and sealing gasket 122.

The fuel unit 80 and dispersant unit 82 are fitted together as shown and flanges 86 and 108 are secured together by suitable means such as cap screw 160, nut 162, and sealing gasket 164. A chamber 98 is thereby formed.

The operation of the embodiment of the smoke generator shown in FIGURE 3 is as follows. Upon ignition through the igniter train, the forward end of fuel block 96 burns liberating hot combustion gases which fill chamber 98, contact base 102 and cause the dispersant 150' to melt. The gases pass from chamber 98 into orifice 135, into duct 140 and subsequently into dye reservoir 152 through holes 154- thereby building up pressure on dispersant block 150 and further aiding in the melting thereof. The hot gases also flow from chamber 98 into orifice tube 136 at high velocity and create a low pressure area in the region of the orifice 138 and in chamber 144. The resulting pressure differential causes the melted dispersant to flow through holes 148 into chamber 147, through passageway 146 and into chamber 144 whereby it is aspirated into the gas stream flowing through orifice 138. Subsequently, the dispersant is atomized and vaporized or sublimed by the high velocity gas stream as it flows through chimney duct 134 and into the atmosphere.

Although the invention has been described with reference to specific embodiments in the form of the smoke generator, it is to be understood that it is applicable to other modifications and variations in the types of dispersants, dyes, fuels, etc. which are within the spirit and scope of the invention.

We claim:

1. A smoke generator comprising a container having a side wall, a rearward closed end, and a forward end having an outlet therein, a fuel-containing reservoir adjacent to said rearward end of the container, a dispersant-containing reservoir between the container outlet opening and the fuel-containing reservoir, spaced concentric inner and outer flue means disposed through said dispersant reservoir, the forward end of the inner flue means communicating with the outlet at the forward end of the container, a nozzle having a flow control passage therethrough providing communication between the fuel-containing reservoir and the rearward end of the inner flue means, restricted passage means in said nozzle providing communication between the fuel-containing reservoir and the space between the inner and outer flue means, the forward end of the outer flue having at least one aperture therethrough to provide communication between the forward end of the dispersant reservoir and the space between the inner and outer flue means, duct means providing communication between the rearward part of the dispersant reservoir and the flow control passage in said nozzle, and ignition means for fuel in the fuel-containing reservoir.

2. A smoke generator comprising a container having a side wall, a rearward closed end, and a forward end having an outlet therein, a fuel-containing reservoir adjacent to said rearward end of the container, a dispersant-containing reservoir between the container outlet opening and the fuel-containing reservoir, spaced concentric inner and outer flue means disposed through said dispersant reservoir, the forward end of the inner flue means communicating with the outlet at the forward end of the container and adapted to disperse smoke into the atmosphere, a nozzle having a flow control passage therethrough providing communication between the fuel-containing reservoir and the rearward end of the inner time means, restricted passage means in said nozzle providing communication between the fuel-containing reservoir and the space between the inner and outer flue means thereby to direct products of combustion thereinto, the forward end of the outer flue having at least one aperture therethrough to provide communication between the forward end of the dispersant reservoir and the space between the inner and outer flue means whereby products of combustion may pass to the upper end of the dispersant-containing reservoir, duct means providing aspirating communication between the rearward part of the dispersant reservoir and the flow control passage in said nozzle, and ignition means for fuel in the fuel-containing reservoir.

3. A smoke generator comprising a tubular container having a sealed rearward closed end, and a forward end having an outlet opening therein, a diverging chimney communicating with the outlet opening, an annular dispersant-containing reservoir means adjacent to said forward open end rearward of the chimney, a cylindrical fuel-containing reservoir means adjacent to said rearward end, said dispersant reservoir means including a base member provided with a central opening therethrough, said dispersant and fuel reservoir means being joined together by said base member, aspirating nozzle mean comprising first and second orifice means disposed within the central opening of said base member, spaced concentric inner and outer wall means disposed through said dispersant reservoir, said wall means defining an inner duct and an annular duct, said inner duct providing communication between said first orifice means in said nozzle and the rearward end of said diverging chimney, said outer wall means provided with at least one aperture near the forward end thereof whereby said annular duct and said aperture provide communication between said second orifice means in the nozzle and the forward part of said dispersant reservoir adapted to direct products of combustion thereinto, third orifice means communicating with the rearward part of said dispersant reservoir and disposed in aspirating relationship with said first orifice means, and ignition means for fuel in the fuel-containing reservoir.

4. A smoke generator comprising a tubular container having a sealed rearward closed end, and a forward end having an outlet opening therein, a diverging chimney communicating with the outlet opening, an annular dispersant-containing reservoir means adjacent to said forward open end rearward of the chimney, a block of dimethylamino-azo-benzene in the dispersant-containing reservoir, a cylindrical fuel containing reservoir means adjacent to said rearward end, a block of fuel comprising charcoal, anthracene, ammonium nitrate and linseed oil in said fuel containing reservoir, said dispersant reservoir means including a base member provided with a central opening therethrough, said dispersant and fuel reservoir means being joined together by said base member, aspirating nozzle means comprising :first and second orifice means disposed within the central opening of said base member, spaced concentric inner and outer wall means disposed through said dispersant reservoir, said wall means defining an inner duct and an annular duct, said inner duct providing communication between said first orifice means in said nozzle and the rearward end of said diverging chimney, said outer wall means provided with at least one aperture near the forward end thereof whereby said annular duct and said aperture provide communication between said second orifice means in the nozzle and the forward part of said dispersant reservoir adapted to direct products of combustion thereinto, third orifice means communicating with the rearward part of said dispersant reservoir and disposed in aspirating relationship with said first orifice means, and ignition means for fuel in the fuel-containing reservoir. i

References Cited in the file of this patent UNITED STATES PATENTS 2,605,703 Lawson Aug. 5, 1952 2,633,455 Finkelstein et al Mar. 31, 1953 2,882,239 Comings et al. Apr. 14, 1959 2,995,526 De Ment Aug. 8, 1961 OTHER REFERENCES Colored Signal Smokes, by Technical Command, Chemical Warfare Service; Chemical and Engineering News, vol. 22, No. 22, November 25, 1944 (page 1991, or second of copy, relied upon). (Copy in Div. 64.) 

